AWK数组变量的级联 - 意外行为 [英] Concatenation of AWK array variables - unexpected behaviour

问题描述

输入文件

steve,apples
steve,oranges
john,pears
john,oranges
mary,bananas
steve,plums
mary,nactarines

我要得到这样的输出：

I want to get output like this:

steve:apples,oranges,plums
john:pears,oranges
mary:bananas,nectarines

下面是单行我一直在试图让工作：

Here is the one liner I have been trying to get to work:

awk -F, '{if(a[$1])a[$1]=a[$1]","$2; else a[$1]=$2;}END{for (i in a)print i ":" a[i];}' OFS=, inputfile

它给人的输出

,orangesrs
,plumsesples
,nactariness

这样看来，字符串连接 A [$ 1] = A [$ 1]，$ 2 是导致数组元素的原始值将被覆盖到一定程度上。我怎样才能开展这项拼接是否正确？

It would appear that the string concatenation a[$1]=a[$1]","$2 is resulting in the original value of the array element to be overwritten to some degree. How can I carry out this concatenation correctly?

顺便说一句，我得到的Centos相同的结果，和Mac OSX。

Incidentally, I get the same results on Centos, and Mac OSX.

推荐答案

您可以试试这个：

awk -F, '{a[$1]=(a[$1]?a[$1]FS$2:$2)} END {for (i in a) print i":"a[i]}' file
mary:bananas,nactarines
john:pears,oranges
steve:apples,oranges,plums

PS发布后，我看到，这是一样的肯特公布，但没有资料为什么删除。

PS After posted it, I see that this is the same as Kent posted, but no info on why deleted.

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